# Thread: X, Y & Z...Is it only me????

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Originally Posted by Henro

I know this should be simple. Is it, and am I just anal retentive or something similar?
It is simple, you're just being anal retentive(well not really, just asking questions). Pretty simple, we've all figured that Z is about the rotational axis. Now XY is simply a perpendicular plane to Z.

Which direction X and Y are are pretty much open to where they lay. Convention is that X+ is to the right (tool travel, not table travel), and Y is away or up Much like a graph on your desk, Y+ is away (verticle mill), if that same graph is on your computer screen, Y+ is up(horizontal mill).

As for the lathe question, primary rotational axis is Z, so the spindle, really has nothing to do with where the tool is. It also has nothing to do with weather or not the headstock moves. Like on mill, X+ is to the right, funny thing is when you move to the right, table goes to the left, the thing that counts(the tool) that goes to the right never actually moves(in our frame of reference).

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Originally Posted by Henro
Hi all,

The example that Bob G provided says that the Z axis is positive in the direction that increases the distance between the work piece and the cutting tool. Well in the lathe, the distance between the cutting tool and the work is set by the cross travel or compound or combination of both. NOT by the headstock...which we want to call Z even though it is not holding a tool like it would be in a mill.

So...are there two independent standards for X, Y, and Z, dependent on whether the tool is rotating, or the work is rotating?

...
Think of it more as X,Y,Z defining the point in space where contact is made and not as to weather the tool or the part is moving.

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## Rule of thumb and two fingers

I saw an explanation of x, y and z with the use of the thumb, index finger and middle finger. You had to move the orientation of your hand to address the machine, but....it made sense. I'll try to find it.
Chris

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Originally Posted by Hollowbuilt
I saw an explanation of x, y and z with the use of the thumb, index finger and middle finger. You had to move the orientation of your hand to address the machine, but....it made sense. I'll try to find it.
Chris
http://en.wikipedia.org/wiki/Right-hand_rule

http://www.uni-duesseldorf.de/URZ/ha...bas/b_coor.htm
Last edited by smiller6912; 10-01-2009 at 10:41 PM.

5. gnm109 Guest
Originally Posted by beanbag
main thing to be careful of is that you keep track whether the DRO is reading in radius or diameter mode (even on the mill).
Exactky. That's the key difference. When the Mituyo is toggled to lathe use, it will read .005 per .001 to give radius readings on the cross slide (I wonder which axis that would be. LOL. )

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I would say X,Y,Z works just fine on a say a vertical mill, because the tool movement in X,Y,Z also produces dimensions on the workpiece in X,Y,Z.

But a simple lathe isn't a vertical mill on its side... I think the conceptual difficulty with using X,Y,Z on a lathe is that because the workpiece is revolving, the relationship between the cutting tool and the workpiece actually has only two dimensions:-

1) the distance of the cutting point along the spindle/workpiece axis
2) the distance of the cutting point from the spindle/workpiece axis

So unlike the vertical mill, the correspondence between the X,Y,Z of the lathe and the X,Y,Z of the workpiece is indirect, and labelling the axes on the lathe is more a matter of convention/convenience rather than fundamental geometry.

Cheers
.

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## All plane to see?

And now - following on:

Originally Posted by oldtiffie
This is for "starters" - I will post more later that should clarify things some-what:
..................................................

Common Codes
G-codes are also called preparatory codes, and are any word in a CNC program that begins with the letter 'G'. Generally it is a code telling the machine tool what type of action to perform, such as:

rapid move
controlled feed move in a straight line or arc
series of controlled feed moves that would result in a hole being bored, a workpiece cut (routed) to a specific dimension, or a decorative profile shape added to the edge of a workpiece.
change a pallet
set tool information such as offset.
There are other codes; the type codes can be thought of like registers in a computer

X absolute position
Y absolute position
Z absolute position
A position (rotary around X)
B position (rotary around Y)
C position (rotary around Z)
U Relative axis parallel to X
V Relative axis parallel to Y
W Relative axis parallel to Z

.................................................. ........
The point of origin (zero on all axis) and the planes and directions of "X", "Y" and "Z" (as well as "A", "B" and "C") are shown on the following pic/diagram.

[Edit:
the sketch has been revised to correct the X-Z plane tag as advised by Glenn Wagman.
End edit]

It is plotted exactly the same as three-dimensional graphs in Math 101.

It is also exactly the same as in a CAD drawing where each plane and the direction/s of the "X", "Y" and "Z" co-ordinates and the point of origin (the "start" or "all the zeroes" point ) are located.

The "pointer" is an infinitely small point that emulates the pencil points and lines, arcs etc. on a graph as the "pencil" or "point" moves over the static axis and planes.

The "picks" on a "mouse" on a CAD drawing move over the drawing in exactly the same way.

On a vertical mill:
- the "pointer" is fixed at the centre of the spindle axis;
- "X" is left-right as is co-incident with the table "X" direction;
- "Y" is in-out and is co-incident with the table "Y" direction;
- "Z" is the point of the pointer and is co-incident with the quill spindel axis;
- the table is the "X"-"Y" plane;
- for the pointer to be postioned to a +ve direction of "X" the table must be moved "left" in the "X" direction;
- for the pointer to be positioned to a +ve direction in the direction of "Y" the table must be moved "out" (toward the front of the mill);
- for the pointer to be positioned to a +ve direction in the direction of "Z", either the quill must be raised (as on a square or round column mill) or the table lowered by lowering the knee (as on a BP or "Turret" type mill).

There are variations to thse rules for some other mills as well as lathes and grinders etc. I will or may cover those topics later.
Last edited by oldtiffie; 10-02-2009 at 08:45 AM.

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There are no "rules". It is completely arbitrary. The only governing body in this matter is convention. It much depends on your background. If you are a mathematician then X is left/right, Y is up/down and Z is in/out of the paper. Same for computer graphics and even CAD. How they may be oriented also depends on your viewpoint.

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oldtiffie,

The pink one should be X Z Plane, not X Y as you have it marked.

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## Oops

Thanks Glenn.

So 'tis.

'nuvva day - 'nuvva cock-up. SNAFU??

I will amend it later.

I will also cover some variations to it as well - lathe, gantry mill etc. etc.

[Edit:

Thanks Glenn.

All done 'n' dusted.

End edit]
Last edited by oldtiffie; 10-02-2009 at 08:47 AM.

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